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Step 2.2 Comparing Exposure Doses to Health Guidelines

Although health assessors evaluate all adverse health effects, the method of evaluation for cancer-related health effects differs from the methods used to evaluate noncancer health effects. When evaluating noncancer health effects, health assessors use the following health guidelines.

Guideline

Source

MRL

minimal risk level

(ATSDR's minimal risk levels are doses of a chemical that are unlikely to result in noncancer health effects.)

ATSDR

RfD

reference dose

(EPA's reference doses are estimates of ingested doses to a chemical that are unlikely to result in noncancer health effects.)

EPA

RfC

reference concentration

(EPA's reference concentrations are estimates of daily exposures to a chemical that are unlikely to result in noncancer health effects. Reference concentrations apply to possible noncancer effects from breathing a chemical.)

EPA

The health assessor compares the exposure dose (the amount of the chemical that people are actually contacting) to the minimal risk level (or another guideline). If the exposure dose is higher than the health guideline, the exposure is further evaluated. If the exposure dose is lower than the health guideline, noncancer effects are unlikely to occur, but if the chemical could cause cancer, the health assessor will evaluate the chemical further.